Several bis(formylphenyl) compounds have been know where a phenolic hydroxyl group in the molecular structure is protected by an acid-dissociable dissolution suppressing group. For example, Literature 1 describes a bis(formylphenyl) where three phenolic hydroxyl groups are each bonded via single bond with a phenyl ring substituted by an alkoxycarbonylmethyl group.
Also, Literature 2 describes a bis(formylphenyl) compound comprising phenolic hydroxyl groups of methylene bis(salicylaldehyde) each substituted by an alkoxycarbonylmethyl group.
In addition, there are polynuclear polyphenol compounds having their phenolic hydroxyl group protected by an acid-dissociable dissolution suppressing group, wherein the phenolic hydroxyl group of such each polynuclear polyphenol compound comprising formyl groups of a bis(formylphenyl) compound each bonded with two hydroxyphenyl groups. For example, Literature 3 describes a polynuclear polyphenol compound whose hydroxyl groups are randomly substituted by acid-dissociable dissolution suppressing groups by approx. 25 to 40 mol %. Also, Literature 4 describes a polynuclear polyphenol compound whose two hydroxyl groups in the bis(hydroxyphenyl) base skeleton are substituted by acid-dissociable dissolution suppressing groups.
In certain fields, however, such as the field of photo-sensitive resist materials, for example, there have been calls in recent years for improvement of resist resolution, heat resistance and contrast, especially the alkali solubility or alkali solution speed in an alkali developing agent of the portions where dissolution suppressing groups have been eliminated, and improvements are expected in bis(formylphenyl) compounds and polynuclear polyphenol compounds that are used as materials for traditionally known polynuclear phenol compounds based on substitution by acid-dissociable dissolution suppressing groups.
Patent Literature
[Non-Patent Literature 1] European Journal of Organic Chemistry, 2000, 1923-1931
[Patent Literature 2] Japanese Patent Laid-open No. 2007-39381
[Patent Literature 3] Japanese Patent Laid-open No. 2006-267996
[Patent Literature 4] International Patent Laid-open No. W02007-034719